1. Field of the Invention
The present invention relates to a charged-particle detector which is disposed in a vacuum chamber of a mass spectroscope or the like, to detect ions or electrons.
2. Related Background Art
A mass spectroscope performs mass spectrometry of ions by utilizing the fact that ions flying in a specific place differ in trajectory or velocity depending on their mass. That is, in the case in which ions are deflected by an electric field and/or a magnetic field, their deflection amounts are different depending on their mass, and therefore, the incoming positions of the ions to an ion detector are different depending on their mass. Further, in the case in which ions are accelerated in an electric field, the flying velocities of the accelerated ions are different depending on their mass, and therefore, the incoming timings of the ions to the ion detector are different depending on their mass.
A mass spectroscope utilizing the latter principle is called a TOF (Time of Flight) type mass spectroscope. In a TOF type mass spectroscope, an ion having a different flying velocity because of its different mass is detected by an ion detector, and a time until the ions reach the ion detector is measured. Such a TOF type mass spectroscope is described in, for example, Patent Document 1 (U.S. Pat. No. 5,770,858), and a micro-channel plate (MCP) is used as an ion detector.